Building codes today require that certain walls of wood or steel framed buildings be capable of taking shear loads. Typically, ⅜ inch to ⅝ inch wood-based sheathing have been installed on the interior or exterior side of the framing studs to take such shear loads. It is common practice to install ½ inch to ⅝ inch thick drywall panels, such as gypsum wallboards, on the interior sides of the framing studs and a ⅞ inch stucco system or other suitable material with a water-resistive barrier on the exterior side of the framing studs.
In general, most wall board systems used in construction are susceptible to water and moisture intrusion, which can cause water damage and corrosion. Internal (hydration) cracks and external (stress) cracks, which can form as a result of installation error or building movement, can increase the amount of damage caused by the water intrusion.
Specifically, wood-based sheathing, lath and organic water-resistive barriers (such as building paper), which are used in typical stucco systems, are particularly susceptible to corrosion caused by water. For example, in a typical one-coat stucco system 100, wood-based sheathing such as plywood or OSB 110 is attached to studs/framing 120 using mechanical fasteners (not shown), as shown in FIG. 1. A water-resistive barrier 130 such as Grade D building paper is then attached to the wood-based sheathing 110 using staples (not shown). A one-inch tongue and groove foam insulation board 140, with woven wire lath 150 attached thereto, is then attached to the water-resistive barrier 130 using staples (not shown). A ⅜ inch brown coat 160 and a ⅛ inch finish coat 170 are then applied to the wire lath 150.
Similarly, in a three-coat stucco system 200 shown in FIG. 2, wood-based sheathing 210 is attached to studs/framing 220 using mechanical fasteners (not shown), as shown in FIG. 2. A water-resistive barrier 230 such as Grade D building paper 230 is then attached to the wood-based sheathing 210 using staples (not shown). A woven wire or expanded metal lath 240 is attached to the water-resistive barrier 230 using staples (not shown). A ⅜ inch scratch coat 250 is then applied over the water-resistive barrier 230 through the lath 240. A ⅜ inch brown coat 260 and a ⅛ inch finish coat 270 are then applied over the scratch coat 250 by hand or using a machine applicator (not shown).
In both the one-coat and three-coat systems described above, water can infiltrate the stucco layers, which can cause corrosion of the lath, water-resistive barrier, and wood-based sheathing. Accordingly, a new type of exterior wall board system is needed to solve these problems.
In a typical Exterior Insulation Finish System (EIFS) shown in FIG. 3, interior gypsum wallboard 305 is attached to the inside of the studs/framing 320 using mechanical fasteners (not shown). Glassmat gypsum sheathing 310 is attached to the outside of the studs/framing 320 using mechanical fasteners (not shown). A fluid-applied water/air barrier 340 is applied on the Glassmat gypsum sheathing 310. An adhesive layer 330 is applied to the fluid-applied water/air barrier 340 to bond a non-structural EPS foam insulation board 350 to the fluid-applied water/air barrier 340. Drainage channels 355 are formed in the EPS foam insulation board 350 by cutting out vertical strips in the EPS foam insulation board 350. A reinforcing mesh 360 is adhered to the EPS insulation board 350 followed by a base coat 370 and a finish coat 380. Some of the disadvantages of an EIFS 300 are that it does not provide sufficient shear force resistance and its inherent frailty would make it less durable and more susceptible to damage from exterior forces when compared to other cement-based, masonry-based, or wood-based wall systems. For example, naturally occurring solar heat may melt the EPS foam causing it to prematurely delaminate and the lower (reachable) surface may be prone to exterior impact damage.]
Another problem with the aforementioned wall board systems is that the system is complicated and produces a lot of waste materials, which makes clean up more burdensome.